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Background: The effect of helicobacter pylori either in provoking or protecting GERD is unclear and the results of studies are conflicting. We aimed to study the effect of H.pylori eradication on GERD by 24-hour ph monitoring. Materials and methods: 14 patients with duodenal ulcer or erosive duodenitis without any endoscopic and clinical evidences of GERD were enrolled. 24-hour ph monitoring were performed before and 12 month after H-Pylori eradication. The score was based on DeMeester scoring system. H.Pylori was diagnosed by rapid urease test before eradication and by urea breath test (UBT) after eradication. Results: The mean age was 41.610.2 years. The mean scores of 24-hour ph monitoring were 6.84.3 and 5.43.9 before and after eradication, respectively. The differences were not statistically significant (NS). Epigastric pain changed significantly before and after the therapy (p<0.01). Conclusion: H.pylori eradication did not have any effect on scores of 24-hour esophageal ph monitoring. Epigastric pain significantly decreased after eradication.

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Background: Because of widespread interests to biopreservatives, several studies have been conducted within last decades that show the nisin has been used as a preservative to control food borne spoilage microorganisms. The aim of this study was to evaluate anti-bacterial activity of nisin and its effect on decreasing concentration of current chemical preservatives.
Materials and methods: In this experimental study, anti-bacterial activity of nisin and its effect on decreasing concentration of usual chemical preservatives against Staphylococcus aureus (PTCC 1112) and Listeria monocytogenes (PTCC 1301) were studied. The study was performed in two steps. First, MIC (minimum inhibitory concentration) and MBC (minimal bactericidal concentration) of preservatives, including sodium nitrite, benzoic acid and nisin, were measured in optimum pH (5.5) by serial dilution method. Second, MIC of sodium nitrite and benzoic acid were determined in combination with nisin.
Results: Sodium nitrite, benzoic acid and nisin had antibacterial activities against Staphylococcus aureus and Listeria monocytogenes MIC was 500, 200 and 25 ppm for Staphylococcus aureus, and 100, 200 and 10 ppm for Listeria monocytogenes, respectively. Niacin reduced MIC of sodium nitrite and benzoic acid to 200 and 50 ppm for Staphylococcus aureus, and 25 and 25 ppm for Listeria monocytogenes, respectively. Conclusion: The nisin reduces chemical preservatives concentration required, and it could be used as a safe preservative in food microbiology.